In "Enemy," Jake Gyllenhaal's character finds an exact double of himself in a movie he's watching. The tradition of on-screen dopplegangers is a long and not-always-honorable one, but it's a classic trope none the less.

To honor the two Jakes in "Enemy," I've compiled a by-no-means-exhaustive, definitely-not-definitive list of the best and some of the worst dual roles in cinema history.